Introduction to ClinicalAnatomy1

Blood Vessels 4

Diseases of Blood Vessels 4

Lymphatic System 5

Diseases of the Lymphatic System 5

Nervous System 5

Segmental Innervation of Skin 5

Segmental Innervation of Muscle 5

Clinical Modification of the Activities of the

Autonomic Nervous Systems 5

Mucous and Serous Membranes 5

Mucous and Serous Membranes and Inflammatory

Disease 5

Bones 6

Bone Fractures 6

Rickets 7

Epiphyseal Plate Disorders 7

Clinical Significance of Sex, Race, and Age on Structure 9

Clinical Problem Solving Questions 9

Answers and Explanations 11

Skin 2

Lines of Cleavage 2

Skin Infections 3

Sebaceous Cyst 3

Shock 3

Skin Burns 3

Skin Grafting 3

Fasciae 3

Fasciae and Infection 3

Skeletal Muscle 3

Muscle Attachments 3

Muscle Shape and Form 3

Cardiac Muscle 3

Necrosis of Cardiac Muscle 3

Joints 4

Examination of Joints 4

Ligaments 4

Damage to Ligaments 4

Bursae and Synovial Sheaths 4

Trauma and Infection of Bursae and Synovial Sheaths 4

Chapter Outline

SKINLines of CleavageIn the dermis, the bundles of collagen fibers are mostlyarranged in parallel rows. A surgical incision through theskin made along or between these rows causes the mini-mum of disruption of collagen, and the wound heals withminimal scar tissue. Conversely, an incision made acrossthe rows of collagen disrupts and disturbs it, resulting in themassive production of fresh collagen and the formation of abroad, ugly scar. The direction of the rows of collagen isknown as the lines of cleavage (Langer’s lines), and theytend to run longitudinally in the limbs and circumferen-tially in the neck and trunk (CD Fig. 1-1). CD Figure 1-1 Cleavage lines of the skin.

A general knowledge of the direction of the lines ofcleavage greatly assists the surgeon in making incisions thatresult in cosmetically acceptable scars. This is particularlyimportant in those areas of the body not normally coveredby clothing. A salesperson, for example, may lose his or herjob if an operation leaves a hideous facial scar.

Skin InfectionsThe nail folds, hair follicles, and sebaceous glands arecommon sites for entrance into the underlying tissues ofpathogenic organisms such as Staphylococcus aureus.Infection occurring between the nail and the nail fold iscalled a paronychia. Infection of the hair follicle and seba-ceous gland is responsible for the common boil. A carbuncleis a staphylococcal infection of the superficial fascia. It fre-quently occurs in the nape of the neck and usually starts as aninfection of a hair follicle or a group of hair follicles.

Sebaceous CystA sebaceous cyst is caused by obstruction of the mouth of asebaceous duct and may be caused by damage from a combor by infection. It occurs most frequently on the scalp.

ShockA patient who is in a state of shock is pale and exhibits goose-flesh as a result of overactivity of the sympathetic system,which causes vasoconstriction of the dermal arterioles andcontraction of the arrector pili muscles.

Skin BurnsThe depth of a burn determines the method and rate ofhealing. A partial-skin-thickness burn heals from the cells ofthe hair follicles, sebaceous glands, and sweat glands as wellas from the cells at the edge of the burn. A burn that extendsdeeper than the sweat glands heals slowly and from theedges only, and considerable contracture will be caused byfibrous tissue. To speed up healing and reduce the inci-dence of contracture, a deep burn should be grafted.

Skin GraftingSkin grafting is of two main types: split-thickness graftingand full-thickness grafting. In a split-thickness graft thegreater part of the epidermis, including the tips of the der-mal papillae, are removed from the donor site and placed onthe recipient site. This leaves at the donor site for repair pur-poses the epidermal cells on the sides of the dermal papillaeand the cells of the hair follicles and sweat glands.

A full-thickness skin graft includes both the epidermisand dermis and, to survive, requires rapid establishment of a

new circulation within it at the recipient site. The donor siteis usually covered with a split-thickness graft. In certain cir-cumstances the full-thickness graft is made in the form of apedicle graft, in which a flap of full-thickness skin is turnedand stitched in position at the recipient site, leaving the baseof the flap with its blood supply intact at the donor site.Later, when the new blood supply to the graft has beenestablished, the base of the graft is cut across.

FASCIAEFasciae and InfectionKnowledge of the arrangement of the deep fasciae oftenhelps explain the path taken by an infection when it spreadsfrom its primary site. In the neck, for example, the variousfascial planes explain how infection can extend from theregion of the floor of the mouth to the larynx.

SKELETAL MUSCLEMuscle AttachmentsThe importance of knowing the main attachments of allthe major muscles of the body need not be emphasized.Only with such knowledge is it possible to understand thenormal and abnormal actions of individual muscles ormuscle groups. How can one even attempt to analyze,for example, the abnormal gait of a patient without thisinformation?

Muscle Shape and FormThe general shape and form of muscles should also benoted, since a paralyzed muscle or one that is not used (suchas occurs when a limb is immobilized in a splint) quicklyatrophies and changes shape. In the case of the limbs, it isalways worth remembering that a muscle on the oppositeside of the body can be used for comparison.

CARDIAC MUSCLENecrosis of Cardiac MuscleThe cardiac muscle receives its blood supply fromthe coronary arteries. A sudden block of one of the largebranches of a coronary artery will inevitably lead to necro-sis of the cardiac muscle and often to the death of thepatient.

Introduction to Clinical Anatomy 3

clot at the damaged site is invaded by blood vessels andfibroblasts. The fibroblasts lay down new collagen and elas-tic fibers, which become oriented along the lines of me-chanical stress.

BURSAE ANDSYNOVIALSHEATHS

Trauma and Infection of Bursaeand Synovial SheathsBursae and synovial sheaths are commonly the site oftraumatic or infectious disease. For example, the extensortendon sheaths of the hand may become inflamed after ex-cessive or unaccustomed use; an inflammation of theprepatellar bursa may occur as the result of trauma from re-peated kneeling on a hard surface.

BLOOD VESSELSDiseases of Blood VesselsDiseases of blood vessels are common. The surface anatomyof the main arteries, especially those of the limbs, is dis-cussed in the appropriate sections of this book. The collat-eral circulation of most large arteries should be understood,and a distinction should be made between anatomic endarteries and functional end arteries.

All large arteries that cross over a joint are liable to bekinked during movements of the joint. However, the distalflow of blood is not interrupted because an adequate anas-tomosis is usually between branches of the artery that ariseboth proximal and distal to the joint. The alternative bloodchannels, which dilate under these circumstances, form thecollateral circulation. Knowledge of the existence and posi-tion of such a circulation may be of vital importance shouldit be necessary to tie off a large artery that has been damagedby trauma or disease.

Coronary arteries are functional end arteries, and ifthey become blocked by disease (coronary arterial occlusionis common), the cardiac muscle normally supplied by thatartery will receive insufficient blood and undergo necrosis.Blockage of a large coronary artery results in the death of thepatient.

JOINTSExamination of JointsWhen examining a patient, the clinician should assessthe normal range of movement of all joints. Whenthe bones of a joint are no longer in their normalanatomic relationship with one another, then the joint issaid to be dislocated. Some joints are particularly suscep-tible to dislocation because of lack of support by ligaments,the poor shape of the articular surfaces, or the absenceof adequate muscular support. The shoulder joint, tem-poromandibular joint, and acromioclavicular joints aregood examples. Dislocation of the hip is usually congeni-tal, being caused by inadequate development of thesocket that normally holds the head of the femur firmlyin position.

The presence of cartilaginous discs within joints, espe-cially weightbearing joints, as in the case of the knee, makesthem particularly susceptible to injury in sports. Duringa rapid movement the disc loses its normal relationshipto the bones and becomes crushed between the weight-bearing surfaces.

In certain diseases of the nervous system (e.g., sy-ringomyelia), the sensation of pain in a joint is lost. Thismeans that the warning sensations of pain felt when a jointmoves beyond the normal range of movement are notexperienced. This phenomenon results in the destruction ofthe joint.

Knowledge of the classification of joints is of great valuebecause, for example, certain diseases affect only certaintypes of joints. Gonococcal arthritis affects large synovialjoints such as the ankle, elbow, or wrist, whereas tubercu-lous arthritis also affects synovial joints and may start in thesynovial membrane or in the bone.

Remember that more than one joint may receive thesame nerve supply. For example, the hip and knee jointsare both supplied by the obturator nerve. Thus, a patientwith disease limited to one of these joints may experiencepain in both.

LIGAMENTSDamage to LigamentsJoint ligaments are very prone to excessive stretching andeven tearing and rupture. If possible, the apposing damagedsurfaces of the ligament are brought together by positioningand immobilizing the joint. In severe injuries, surgicalapproximation of the cut ends may be required. The blood

4 Chapter 1

LYMPHATICSYSTEM

Diseases of the Lymphatic SystemThe lymphatic system is often de-emphasized by anatomistson the grounds that it is difficult to see on a cadaver. However,it is of vital importance to medical personnel, since lymphnodes may swell as the result of infection, metastases, or pri-mary tumor. For this reason, the lymphatic drainage of all ma-jor organs of the body, including the skin, should be known.

A patient may complain of a swelling produced by theenlargement of a lymph node. A physician must know theareas of the body that drain lymph to a particular node if heor she is to be able to find the primary site of the disease. Of-ten the patient ignores the primary disease, which may be asmall, painless cancer of the skin.

Conversely, the patient may complain of a painful ulcerof the tongue, for example, and the physician must know thelymph drainage of the tongue to be able to determine whetherthe disease has spread beyond the limits of the tongue.

NERVOUS SYSTEMSegmental Innervation of the SkinThe area of skin supplied by a single spinal nerve, andtherefore a single segment of the spinal cord, is called adermatome. On the trunk, adjacent dermatomes overlapconsiderably; to produce a region of complete anesthesia, atleast three contiguous spinal nerves must be sectioned. Der-matomal charts for the anterior and posterior surfaces of thebody are shown in CD Figs. 1-2 and 1-3.

In the limbs, arrangement of the dermatomes is morecomplicated because of the embryologic changes that takeplace as the limbs grow out from the body wall.

A physician should have a working knowledge of thesegmental (dermatomal) innervation of skin, because withthe help of a pin or a piece of cotton he or she can determinewhether the sensory function of a particular spinal nerve orsegment of the spinal cord is functioning normally.

Segmental Innervation of MuscleSkeletal muscle also receives a segmental innervation. Mostof these muscles are innervated by two, three, or four spinalnerves and therefore by the same number of segments of thespinal cord. To paralyze a muscle completely, it is thus nec-essary to section several spinal nerves or to destroy severalsegments of the spinal cord.

Learning the segmental innervation of all the musclesof the body is an impossible task. Nevertheless, the segmen-tal innervation of the following muscles should be knownbecause they can be tested by eliciting simple musclereflexes in the patient (CD Fig. 1-4):

■ Biceps brachii tendon reflex: C5 and 6 (flexion of theelbow joint by tapping the biceps tendon)

■ Triceps tendon reflex: C6, 7, and 8 (extension of theelbow joint by tapping the triceps tendon)

■ Brachioradialis tendon reflex: C5, 6, and 7 (supinationof the radioulnar joints by tapping the insertion of thebrachioradialis tendon)

■ Abdominal superficial reflexes (contraction of underly-ing abdominal muscles by stroking the skin): Upperabdominal skin T6–7, middle abdominal skin T8–9, andlower abdominal skin T10–12

■ Patellar tendon reflex (knee jerk): L2, 3, and 4 (exten-sion of the knee joint on tapping the patellar tendon)

■ Achilles tendon reflex (ankle jerk): S1 and S2 (plantarflexion of the ankle joint on tapping the Achillestendon)

Clinical Modification of theActivities of the AutonomicNervous SystemMany drugs and surgical procedures that can modify theactivity of the autonomic nervous system are available. Forexample, drugs can be administered to lower the bloodpressure by blocking sympathetic nerve endings and causingvasodilatation of peripheral blood vessels. In patients withsevere arterial disease affecting the main arteries of the lowerlimb, the limb can sometimes be saved by sectioning thesympathetic innervation to the blood vessels. This producesa vasodilatation and enables an adequate amount of blood toflow through the collateral circulation, thus bypassing theobstruction.

MUCOUS ANDSEROUSMEMBRANES

Mucous and Serous Membranesand Inflammatory DiseaseMucous and serous membranes are common sites for in-flammatory disease. For example, rhinitis, or the common

Introduction to Clinical Anatomy 5

rections taken by the bony fragments depend not only onthe mechanism of injury, but also on the pull of the mus-cles attached to the fragments. Ligamentous attachmentsalso influence the deformity. In certain situations—forexample, the ileum—fractures result in no deformity be-cause the inner and outer surfaces of the bone are splintedby the extensive origins of muscles. In contrast, a fractureof the neck of the femur produces considerable displace-ment. The strong muscles of the thigh pull the distal frag-ment upward so that the leg is shortened. The very stronglateral rotators rotate the distal fragment laterally so thatthe foot points laterally.

Fracture of a bone is accompanied by a considerablehemorrhage of blood between the bone ends and into the

cold, is an inflammation of the nasal mucous membrane,and pleurisy is an inflammation of the visceral and parietallayers of the pleura.

BONESBone FracturesImmediately after a fracture, the patient suffers severe lo-cal pain and is not able to use the injured part. Deformitymay be visible if the bone fragments have been displacedrelative to each other. The degree of deformity and the di-

6 Chapter 1

transverse cutaneous nerve of neck

supraclavicular nervesanterior cutaneous branch of secondintercostal nerve

upper lateral cutaneous nerve of arm

medial cutaneous nerve of arm

lower lateral cutaneous nerve of armmedial cutaneous nerve of forearm

lateral cutaneous nerve of forearmlateral cutaneous branch ofsubcostal nervefemoral branch of genitofemoralnerve

median nerveulnar nerve

ilioinguinal nervelateral cutaneous nerve of thigh

obturator nervemedial cutaneous nerve of thigh

intermediate cutaneous nerve of thigh

infrapatellar branch of saphenous nerve

lateral sural cutaneous nerve

saphenous nerve

superficial peroneal nervedeep peroneal nerve

C2

C3C4

C5

T2

C6

T1

C8

C7L1

S3

S4

L2

L3

L4

L5

S1

T3

T4

T5T6T7T8T9

T10T11T12

CD Figure 1-2 Dermatomes and dis-tribution of cutaneous nerves on theanterior aspect of the body.

surrounding soft tissue. The blood vessels and the fibroblastsand osteoblasts from the periosteum and endosteum takepart in the repair process.

RicketsRickets is a defective mineralization of the cartilage matrixin growing bones. This produces a condition in which thecartilage cells continue to grow, resulting in excess cartilageand a widening of the epiphyseal plates. The poorly miner-alized cartilaginous matrix and the osteoid matrix are soft,and they bend under the stress of bearing weight. Theresulting deformities include enlarged costochondral junc-tions, bowing of the long bones of the lower limbs, and

bossing of the frontal bones of the skull. Deformities of thepelvis may also occur.

Epiphyseal Plate DisordersEpiphyseal plate disorders affect only children and adoles-cents. The epiphyseal plate is the part of a growing bone con-cerned primarily with growth in length. Trauma, infection,diet, exercise, and endocrine disorders can disturb the growthof the hyaline cartilaginous plate, leading to deformity and lossof function. In the femur, for example, the proximal epiphysiscan slip because of mechanical stress or excessive loads. Thelength of the limbs can increase excessively because of in-creased vascularity in the region of the epiphyseal plate sec-

Introduction to Clinical Anatomy 7

greater occipital nervethird cervical nerve

great auricular nervefourth cervical nerve

lesser occipital nervesupraclavicular nerve

first thoracic nerve

posterior cutaneous nerve of arm

medial cutaneous nerve of armposterior cutaneous nerve of forearmmedial cutaneous nerve of forearmlateral cutaneous nerve of forearm

lateral cutaneous branch of T12

posterior cutaneous branches ofL1, 2, and 3 radial nerve

ulnar nerve

posterior cutaneous branches ofS1, 2, and 3

branches of posterior cutaneousnerve of thighposterior cutaneous nerve of thigh

obturator nerve

lateral cutaneous nerveof calf

sural nerve

saphenous nerve

lateral plantar nerve

medial plantar nerve

C2

C3

C5C6

C5

T2

T1

C7C6

C8

L1S5

S4

S3L2

S2

L3

L5

L4

S1L5

T2T3

T4

T5T6T7T8T9T10T11T12

C4

CD Figure 1-3 Dermatomes and distri-bution of cutaneous nerves on the pos-terior aspect of the body.

8 Chapter 1

C5 and 6

biceps brachii tendon reflex

C5, 6, and 7

C6, 7, and 8

triceps tendon reflex

L2, 3, and 4

patellar tendon reflex

S1 and 2

Achilles tendon reflex

brachioradialistendon

reflex

CD Figure 1-4 Some important tendon reflexes used in medical practice.

ondary to infection or in the presence of tumors. Shorteningof a limb can follow trauma to the epiphyseal plate resultingfrom a diminished blood supply to the cartilage.

CLINICALSIGNIFICANCE OFSEX, RACE, ANDAGE ON STRUCTURE

The fact that the structure and function of the human bodychange with age may seem obvious, but it is often over-looked; a child is just not a small adult. A few examples ofsuch changes are given here:

1. In the infant, the bones of the skull are more resilientthan in the adult, and for this reason fractures of theskull are much more common in the adult than in theyoung child.

2. The liver is relatively much larger in the child than inthe adult. In the infant, the lower margin of the liver ex-tends inferiorly to a lower level than in the adult. Thisis an important consideration when making a diagnosisof hepatic enlargement.

3. The urinary bladder in the child cannot be accommo-dated entirely in the pelvis because of the small size ofthe pelvic cavity and thus is found in the lower part ofthe abdominal cavity. As the child grows, the pelvis en-larges and the bladder sinks down to become a truepelvic organ.

4. At birth, all bone marrow is of the red variety. Withadvancing age, the red marrow recedes up the bones of the limbs so that in the adult it is largelyconfined to the bones of the head, thorax, andabdomen.

5. Lymphatic tissues reach their maximum degree of de-velopment at puberty and thereafter atrophy, so the vol-ume of lymphatic tissue in older persons is considerablyreduced.

Introduction to Clinical Anatomy 9

examination, she has severe right lateral flexion defor-mity of the vertebral column.

2. The following statement is correct about this case:A. The virus of poliomyelitis attacks and always destroys

the motor anterior horn cells of the spinal cord.B. The disease resulted in the paralysis of the muscles

that normally laterally flex the vertebral column onthe left side.

C. The muscles on the right side of the vertebral col-umn are hyperactive.

D. The right lateral flexion deformity is caused by theslow degeneration of the sensory nerve fibers origi-nating from the vertebral muscles on the right side.

A 20-year-old woman severely sprains her left ankle whileplaying tennis. When she tries to move the foot so thatthe sole faces medially, she experiences severe pain.

3. What is the correct anatomic term for the movement ofthe foot that produces the pain?A. PronationB. InversionC. SupinationD. Eversion

Read the following case histories/questions and give

the best answer for each.

A 45-year-old patient has a small, firm, mobile tumoron the dorsum of the right foot just proximal to the base of the big toe and superficial to the bones andthe long extensor tendon but deep to the superficialfascia. The patient has a neurofibroma of a digitalnerve.

1. The following information concerning the tumor iscorrect:A. It is situated on the lower surface of the foot close to

the root of the big toe.B. It is attached to the first metatarsal bone.C. On palpation, it moves more freely from medial to

lateral than from proximal to distal.D. It lies deep to the tendon of the extensor hallucis

longus muscle.E. It is attached to the capsule of the metatarsopha-

langeal joint of the big toe.

A 31-year-old woman has a history of poliomyelitis af-fecting the anterior horn cells of the lower thoracic andlumbar segments of the spinal cord on the left side. On

Clinical Problem Solving Questions

A woman recently took up employment in a factory.She is a machinist, and for 6 hours a day she has tomove a lever repeatedly, which requires that she extendand flex her right wrist joint. At the end of the secondweek of her employment, she began to experience painover the posterior surface of her wrist and noticed aswelling in the area.

8. The following statements concerning this patient arecorrect except which?A. Extension of the wrist joint is brought about by

several muscles that include the extensor digitorummuscle.

B. The wrist joint is diseased.C. Repeated unaccustomed movements of tendons

through their synovial sheaths can produce trau-matic inflammation of the sheaths.

D. The diagnosis is traumatic tenosynovitis of the longtendons of the extensor digitorum muscle.

A 19-year-old boy was suspected of having leukemia. Itwas decided to confirm the diagnosis by performing abone marrow biopsy.

9. The following statements concerning this procedureare correct except which?A. The biopsy was taken from the lower end of the

tibia.B. Red bone marrow specimens can be obtained from

the sternum or the iliac crests.C. At birth, the marrow of all bones of the body is red

and hematopoietic.D. The blood-forming activity of bone marrow in

many long bones gradually lessens with age, andthe red marrow is gradually replaced by yellowmarrow.

A 22-year-old woman had a severe infection under thelateral edge of the nail of her right index finger. On ex-amination, a series of red lines were seen to extend upthe back of the hand and around to the front of the fore-arm and arm, up to the armpit.

10. The following statements concerning this patient areprobably correct except which?A. Palpation of the right armpit revealed the presence

of several tender enlarged lymph nodes (lym-phadenitis).

B. The red lines were caused by the superficial lym-phatic vessels in the arm, which were red and in-flamed (lymphangitis) and could be seen throughthe skin.

C. Lymph from the right arm entered the bloodstreamthrough the thoracic duct.

D. Infected lymph entered the lymphatic capillariesfrom the tissue spaces.

A 25-year-old man has a deep-seated abscess in the pos-terior part of the neck.

4. The following statement is correct concerning theabscess:A. The abscess probably lies superficial to the deep

fascia.B. The deep fascia does not determine the direction of

spread of the abscess.C. The abscess would be incised through a vertical skin

incision.D. The lines of cleavage are not important when

considering the direction of skin incisions.E. The abscess would be incised, if possible, through a

horizontal skin incision.

A 40-year-old workman received a severe burn onthe anterior aspect of his right forearm. The area of theburn exceeded 4 in.2 (10 cm2). The greater part ofthe burn was superficial and extended only into thesuperficial part of the dermis.

5. In the superficially burned area, the epidermis cellswould regenerate from the following sites except which?A. The hair folliclesB. The sebaceous glandsC. The margins of the burnD. The deepest ends of the sweat glands

6. In a small area the burn penetrated as far as the superfi-cial fascia; in this region, the epidermal cells wouldregenerate from the following sites except which?A. The ends of the sweat glands that lie in the superfi-

cial fasciaB. The margins of the burnC. The sebaceous glands

In a 63-year-old man, a magnetic resonance imagingscan of the lower thoracic region of the vertebral col-umn reveals the presence of a tumor pressing on thelumbar segments of the spinal cord. He has a loss ofsensation in the skin over the anterior surface of the leftthigh and is unable to extend his left knee joint. Exam-ination reveals that the muscles of the front of the leftthigh have atrophied and have no tone and that theleft knee jerk is absent.

7. The following statements concerning this patient arecorrect except which?A. The tumor is interrupting the normal function of the

efferent motor fibers of the spinal cord on the left side.B. The quadriceps femoris muscles on the front of the

left thigh are atrophied.C. The loss of skin sensation is confined to the der-

matomes L1, 2, 3, and 4.D. The absence of the left knee jerk is because of

involvement of the first lumbar spinal segment.

10 Chapter 1

Introduction to Clinical Anatomy 11

neck plays an important role in the direction of spreadof a deep-seated abscess. C. The abscess would only beincised through a vertical incision if a horizontal inci-sion along a line of cleavage was not possible. A verticalincision in the neck would result in an unsightly scar.D. The lines of cleavage (see CD Fig. 1-1) are very im-portant when considering the direction of skin inci-sions. However, cosmetic concerns have to take secondplace in life-threatening situations.

5. D is the correct answer. In a superficial burn, the epi-dermal cells would regenerate from the hair follicles,the sebaceous glands, and the margins of the burn.

6. C is the correct answer. The sebaceous glands are lo-cated superficially (see text Fig. 1-4) and are destroyedin deep burns.

7. D is the correct answer. The patellar tendon reflex (kneejerk) involves L2, 3, and 4 segments of the spinal cord.

8. B is the correct answer. The wrist joint is not diseasedin this patient. The swelling on the posterior surface ofthe wrist region was caused by the excessive productionof fluid in the synovial sheaths of the extensor tendonssecondary to repeated and excessive extensor move-ments, a condition called traumatic tenosynovitis.

9. A is the correct answer. In a 19-year-old boy, the bonemarrow at the lower end of the tibia is yellow. A biopsyspecimen of red marrow in an adult, who is suspectedof suffering from leukemia, is easily obtained from theiliac crests or the sternum.

10. C is the correct answer. Lymph from the right upperlimb enters the bloodstream through the right lym-phatic duct.

1. C is the correct answer. The tumor is a neurofibroma ofa small digital nerve. This fact explains why the tumoris relatively superficial and moves with the digital nervemore freely from medial to lateral than from proximalto distal. A. The tumor is situated on the dorsum or up-per surface of the foot. B. The tumor is mobile and notattached to the first metatarsal bone. D. The tumor liessuperficial to the tendon of the extensor hallucis longusmuscle. E. The tumor is mobile and is not attached tothe capsule of the metatarsophalangeal joint.

2. B is the correct answer. The disease infected the ante-rior horn cells, whose axons supply the muscles thatnormally laterally flex the vertebral column on the leftside. A. The virus of poliomyelitis attacks anterior horncells in the spinal cord. The result may be death of thecells and muscle paralysis or, depending on the severityof the attack, the nerve cells may recover and the mus-cle paralysis may also recover. C. The muscles on theright side of the vertebral column are contracting nor-mally against the paralyzed left-sided vertebral muscles.D. The sensory nerves of muscles are unaffected by thepolio virus.

3. B is the correct answer. The movement of the foot sothat the sole comes to face medially is called inversion(see text Fig. 1-3). For a full discussion of the move-ments of inversion and eversion of the foot at the subta-lar and transverse joints of the foot, see text.

4. E is the correct answer. The abscess would be incised,if possible, through a horizontal skin incision along aline of cleavage (see CD Fig. 1-1). A. A deep-seatedabscess in the neck usually lies deep to the superficialfascia and beneath the investing layer of deep cervicalfascia. B. The arrangement of the deep fascia in the

Answers and Explanations